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Roger Cicala tests Lomography's Petzval lens
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PostPosted: Mon Jul 21, 2014 10:19 pm    Post subject: Reply with quote
dan_ wrote:
That was the lens intended for - portraits and close-ups with 3D effect and creamy blur. Corner sharpness is not essential in this kind of photography. And is one of the best lenses for for this kind of photography. To ask it to do sharp landscapes too is absurd.


One more reason to run away from such a lens!

There are tons of short and medium telephoto lenses with excellent performance from close distance to infinity. This is the case, for example, of the excellent Sony Carl Zeiss Sonnar 135mm F1.8 lens, which is much faster than the Sony STF 135mm T4.5, and produces an exquisitely creamy bokeh precisely because of the large aperture.


PostPosted: Mon Jul 21, 2014 10:41 pm    Post subject: Reply with quote
The Sonnar 135mm F1.8 is, probably (I don't have it) a very good lens. The difference between the 2 should be that the Sonnar has creamy bokeh wide opened, when the DOF is very narrow, while the STF smooths the bokeh at moderately closed diaphragms too, with a larger DOF. For portraits and close-ups this is a very desired effect.


PostPosted: Mon Jul 21, 2014 11:05 pm    Post subject: Reply with quote
Gerald wrote:
I did not make a moral judgment of the character of Jim Galli. I just made a technical analysis of one of his photos. I did not say that his picture is forged as it was done in the era of Stalinism, when political figures that fell in disgrace were deleted from the official photographs and books.

Yes, I continue to think that Galli's photo was "cooked" to achieve a certain effect that his audience likes. Even Ansel Adams manipulated pictures (not with Photoshop, of course, because Photoshop did not exist in his day) and everyone enjoyed and prized Adam's pictures.

Why people get outraged when someone says that a photo has been manipulated with Photoshop? Maybe be because Photoshop is modern.


Just admit you were wrong and stop preaching at people like you know more than everyone else.


PostPosted: Mon Jul 21, 2014 11:31 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Just admit you were wrong and stop preaching at people like you know more than everyone else.


“Great minds discuss ideas. Average minds discuss events. Small minds discuss people.” Eleanor Roosevelt

Grow up and get off my tail, Mister!


PostPosted: Tue Jul 22, 2014 2:02 am    Post subject: Reply with quote
Gerald wrote:


“Great minds discuss ideas. Average minds discuss events. Small minds discuss people.” Eleanor Roosevelt


And narrow minds are angered by all people that have different ideas. - bernhardas


PostPosted: Tue Jul 22, 2014 6:25 am    Post subject: Reply with quote
Gerald wrote:
...
There are tons of short and medium telephoto lenses with excellent performance from close distance to infinity. This is the case, for example, of the excellent Sony Carl Zeiss Sonnar 135mm F1.8 lens, which is much faster than the Sony STF 135mm T4.5, and produces an exquisitely creamy bokeh precisely because of the large aperture.


The 135/1.8 creats a lot off blur, and this results often in overlapping blur - what some call soft bokeh.
But real soft bokeh is when a single unsharp light spot results in a blur spot with fuzzy edges. The Sony 135/1.8 creates normal sharp blur edges. The point spread function is more or less the transmission curve of the iris - zero, one, zero at most normal lenses. With the STF it is like a Gaussian curve (as long as not over exposed).
Lenses with not exact corrected Spherical Aberration can create more Gaussian like curves - but they loose sharpness (sometimes this happens in distances where the lenses are not good corrected).

For people who like maximum blur the Sony Zeiss 135/1.8 is much better than the STF. For those wo say "much blur = good bokeh" a big entrance pupil and fast-f-numbers are the best. But for those who prefer bokeh quality more than blur quantity lenses with apodization filters are great!


PostPosted: Tue Jul 22, 2014 6:43 am    Post subject: Reply with quote
ZoneV wrote:
Gerald wrote:
...
Maybe you should complain to BH Photo Video that lists the Sony 135mm F/2.8 [T4.5] STF lens as a soft focus lens:
..

Likely they have not much knowledge - or they want to sell lenses to people with not much knowledge.
...


Sony writes less nonsens than BH Photo Video store. Nothing about Softfocus on the German and US site. But on the US site it is a "zoom" in the caption.
http://www.sony.de/electronics/kamera-objektive/sal135f28
http://store.sony.com/135mm-f2.8-t4.5-stf-telephoto-zoom-lens-zid27-SAL135F28/cat-27-catid-All-Full-Frame-A-Mount-Lenses

Regarding the sharpness: A bit stopped down the quality at infinity seems good enough for normal photography - my opinon from some other real images on the net.


PostPosted: Tue Jul 22, 2014 8:44 am    Post subject: Reply with quote
Gerald wrote:

Sharp lens? Kurt Munger found out that the Sony 135mm F/2.8 [T4.5] wide open is poor in the center and crappy at the corners.


yeah... horrible lens... thats why Magnus Wedberg writes:

Quote:

Sharpness
Very good. Sharpness seems to be excellent both in the center and the corners. I haven't actually made enlargements, though, so you have to take this with a grain of salt; I have just checked the negatives with a loupe and looked at the scans. But from the look of this, I would definitely say that this lens is on par with the G glass I own.


the Dyxum Review has a conclusion like this:

Quote:
Excellent build quality, resolution, color and contrast it's making this lens pretty competitive; and in return for not being an AF lens, you get bokeh performance that is simply outstanding.


and all 12 owner on Dyxum give 5 from 5 Points for sharpness. They must all mean stopped down to F8.. which makes sense for a lens which is famous for it's bokeh.

Unlike you I own a Minolta 135mm F2.8 T4.5 STF and know what I'm talking about. And if you want some english charts (FF not APS-C)... look here at photozone.de:

http://www.photozone.de/sonyalphaff/737-sony135f28ff

Quote:
MTF (resolution)

The lens produced very impressive figures in the MTF lab. The center quality is already exceptionally high at T/4.5 (f/2.8 ) whereas the border/corner performance is "just" good to very good. Stopping down to T/5.6 or T/8 increases primarily the border/corner quality although the center receives a slight boost as well. Beyond f/11 diffraction is the limiting factor.

Verdict

The Sony 135mm f/2.8 [T/4.5] STF remains the ultimate cream machine - also in its native full format scope. Regarding the quality of its bokeh (out-of-focus blur) it outclasses all other lenses tested to date so if this is a #1 priority for you just bow to the inevitable and go for it to enjoy images as smooth as silk. That said it doesn't stop here. The lens provides superb results on APS-C DSLRs but it also performs impressively within its native full format. The center quality is excellent at max. aperture and the borders/corners are certainly "sharp enough" here. At T/5.6 the results are very impressive across the image frame. Neither vignetting, distortion nor lateral CAs are something to worry about in field conditions. It is not a perfect lens though - it has its share of "bokeh CAs" (Longitudinal (Axial) Chromatic Aberrations) and it can produce purple fringing in extreme contrast situations. These are minor aspects from a global perspective though. A more significant issue may be the handling of the lens. It is a manual focus lens and you don't even have a focus guidance via the focus indicator in the viewfinder. Due to the special apodisation design the lens "loses" 1 1/2 f-stops (max. T/4.5 @ f/2.8 ) so it may not be the right lens for available-light photography (although super-steady-shot should help here). Regarding the sum of its (special) qualities the verdict can only be "Highly recommended"!


Sounds more for me your Mr. God Munger isn't that good with manualy focussing Wink


Gerald wrote:
Most pictures are of flowers (!) at short distance. Pictures of 3D objects at short distance are not suitable for evaluation of sharpness because the depth of field is very shallow and so most of the subject is out of focus. The best pictures to evaluate the sharpness of a lens are distant landscapes, when the focus is set to infinity.


With a lens which is made for the best possible bokeh? Yeah sure... good joke. I bet you use crops from a 24mm lens for macro because of it's great corner performance at infintiy! Btw.. fisheyes are crap for serious portraits and architecture photagrphy. Laughing



PS: Yes.. the Sony Zeiss 1.8/135 is the sharper and much faster lens, but don't think the bokeh will be anywhere close to the STF.

Last edited by Tedat on Tue Jul 22, 2014 9:32 am; edited 7 times in total


PostPosted: Tue Jul 22, 2014 8:56 am    Post subject: Reply with quote
Gerald wrote:
iangreenhalgh1 wrote:
Just admit you were wrong and stop preaching at people like you know more than everyone else.


“Great minds discuss ideas. Average minds discuss events. Small minds discuss people.” Eleanor Roosevelt

Grow up and get off my tail, Mister!


My Granny used to say "Two wrongs do not make a right". Ian was wrong in saying " . . . like you know more . . .", he should have written " . . . as though you know more . . .". Gerald might have done better not to use Eleanor Roosevelt's patronising quotation, and would certainly have given a better impression of himself by avoiding the intemperate concluding sentence. Verbal brawling does nothing to enhance the reputation of MF Lenses Forum, does it?


PostPosted: Tue Jul 22, 2014 10:26 pm    Post subject: Reply with quote
Tedat wrote:
the Dyxum Review has a conclusion like this:

Quote:
Excellent build quality, resolution, color and contrast it's making this lens pretty competitive; and in return for not being an AF lens, you get bokeh performance that is simply outstanding.


and all 12 owner on Dyxum give 5 from 5 Points for sharpness. They must all mean stopped down to F8.. which makes sense for a lens which is famous for it's bokeh.


Well I prefer to draw my conclusions through analysis of the photographs taken with those lenses. And I learned not to pay much attention to the opinions of owners of expensive and exotic lenses. In general, those people "think" with the heart and not the brain. People usually get enchanted when they buy a lens that costs more than $1000. Would you expect them to say they made a bad deal? In addition, I also know it is not easy to evaluate objectively whether a lens is exceptionally sharp or simply is average. Of course, who buys a $1300 lens will always say that it is very sharp.

Tedat wrote:

Gerald wrote:

Most pictures are of flowers (!) at short distance. Pictures of 3D objects at short distance are not suitable for evaluation of sharpness because the depth of field is very shallow and so most of the subject is out of focus. The best pictures to evaluate the sharpness of a lens are distant landscapes, when the focus is set to infinity.



With a lens which is made for the best possible bokeh? Yeah sure... good joke. I bet you use crops from a 24mm lens for macro because of it's great corner performance at infintiy! Btw.. fisheyes are crap for serious portraits and architecture photagrphy.


Many people think that if a lens was optimized for "infinity", then this lens only provides maximum performance when focused at very, very distant objects like stars, distant galaxies, or maybe the moon. No, guys! A lens optimized for infinity is already at or near its peak performance for any distance equal or greater than about 30 to 40 times the focal length. That is, if a 135mm lens was optimized for infinity, it should perform well for distances greater than about 4m! A logical consequence is that if a 135mm is not sharp for infinity, it is not sharp for 4m, too.

There are a lot of pictures on the internet showing that the Sony 135mm T4.5 STF is soft wide open in the corners for distances just tens of meters away, so it is expected that this lens should be soft wide open in the corners for the typical distances used for portraits. Unfortunately, the vast majority of photos taken with the Sony 135mm T4.5 STF at short-distances are from three-dimensional objects (flowers, animals, etc.) with the background out of focus, thus not allowing an evaluation of sharpness in the corners. Nonetheless, I managed to found some photos, which I'll show later, that prove the Sony 135mm T4.5 STF really is not a stellar performer in the corners even for short distances.


PostPosted: Wed Jul 23, 2014 12:34 am    Post subject: Reply with quote
Unless you've used the 1.8/135 and 4.5/135 STF for a significant number of shots, enough to learn their characters and capabilities then you simply aren't qualified to pass judgment on them.

Experience > Theory


PostPosted: Wed Jul 23, 2014 1:07 am    Post subject: Reply with quote
ZoneV wrote:

The 135/1.8 creats a lot off blur, and this results often in overlapping blur - what some call soft bokeh.
But real soft bokeh is when a single unsharp light spot results in a blur spot with fuzzy edges. The Sony 135/1.8 creates normal sharp blur edges. The point spread function is more or less the transmission curve of the iris - zero, one, zero at most normal lenses. With the STF it is like a Gaussian curve (as long as not over exposed).
Lenses with not exact corrected Spherical Aberration can create more Gaussian like curves - but they loose sharpness (sometimes this happens in distances where the lenses are not good corrected).

For people who like maximum blur the Sony Zeiss 135/1.8 is much better than the STF. For those wo say "much blur = good bokeh" a big entrance pupil and fast-f-numbers are the best. But for those who prefer bokeh quality more than blur quantity lenses with apodization filters are great!

Your analysis is spot on for the general case. However, I think that the case of the Sony STF 135mm T4.5 is a little more complicated. It seems that the designers wanted to deliberately create a lens with strong residual aberration, especially off-axis. I came to this conclusion from the following reasons:

1) A 135mm F2.8 lens can be very well corrected with 5 optical elements. Even with just only 4 elements it is possible to build a reasonably well-corrected 135mm lens. Why then does the Sony 135mm T4.5 STF use 8 optical elements? This high number cannot be explained alone by the relatively short minimum focusing distance of 0.87 m.

2) Despite the high number of optical elements, the Sony 135mm T4.5 STF is soft at the edges for wide open, what suggests that the relatively high number of optical elements was used not to completely correct aberrations, but to allow a controlled level of aberrations to give "character" to the lens.

An evidence that the aim of the optical design was to control, and not to suppress the aberrations, is the unusually strong curvatures of the second optical group, as can be seen in the diagram below.




An optical designer knows that he should avoid strong curvatures if possible because the stronger the curvature of a lens, the more aberrations it generates. Compare the optical design of the Sony 135mm T4.5 STF with the Zuiko 135mm F2.8 and it will be clear that the goal of the strange design of the Sony lens was not the minimization of aberrations.


Zuiko 135mm F2.8:


PostPosted: Wed Jul 23, 2014 5:45 am    Post subject: Reply with quote
at first you suspect because of "missing" MTF charts..

Gerald wrote:

Sony publishes MTF for its 135mm F/2.8 [T4.5] STF lens, but only for the F8 aperture. I suspect it would be a little embarrassing to publish the MTF for wide open. Laughing


than people show where you can find those charts..

Gerald wrote:

Thank you guys, but unfortunately I cannot read Japanese ... The MTF curves appear to be decent, but…

One of the things that has prevented people to believe in lens measurements is the unreliability of MTF curves published. I do not have a Sony 135mm STF lens to measure it, so I will not contest the curves published by Minolta or the Japanese magazine, but certainly they are in contradiction with the review of that lens by Kurt Munger


after that you got a link to a website where they tested the same lens and provided their own MTF chart (in english!).. but since those charts don't proove your opinion.. you just ignore them.


My personal conclusion: testing lenses and reading charts is much more important for you than using a lens for photos. If tests or charts don't proof your point, they are wrong. It's pretty useless to discuss anything with you, so I will stop here and ignore all your future posts.. they are pretty useless for me, you prooved that clearly.


PostPosted: Wed Jul 23, 2014 8:34 am    Post subject: Reply with quote
Gerald wrote:
...
1) A 135mm F2.8 lens can be very well corrected with 5 optical elements. Even with just only 4 elements it is possible to build a reasonably well-corrected 135mm lens. Why then does the Sony 135mm T4.5 STF use 8 optical elements? This high number cannot be explained alone by the relatively short minimum focusing distance of 0.87 m.
...


Do you know that the two elements in the center are the apodization filter?
As far as I know these are not working as a lens cause they have the same refractive index, probably even the same glass.
So there are only 6 lenses left. And these lenses have to correct the aberrations created from the thick parallel plate inside the optical system - the apodization filter.

Gerald wrote:
...
An optical designer knows that he should avoid strong curvatures if possible because the stronger the curvature of a lens, the more aberrations it generates. Compare the optical design of the Sony 135mm T4.5 STF with the Zuiko 135mm F2.8 and it will be clear that the goal of the strange design of the Sony lens was not the minimization of aberrations.
...


The Olympus has a quite unkommen lens design for a 135mm/2.8 Smile
Sonnar types are more common I think, they have stronger curvatures.

Have you seen the US Patent 4062630 (Matsui/Nikon) tele lens setup? There are also lenses with strong curvatures and 6 lenses - to get a f/2 tele lens.
Milton Laikin (author of a lens design book) has published a apochromatic f/11 tele lens, with a heavy bend front lens for SLR use.

Strong lens curvatures are not implicitly generating a high amount of bad optical aberrations, see for example the Topogon lens design - made as top corrected lenses for aerial photography:
http://www.marcocavina.com/articoli_fotografici/Hypergon_Topogon_Biogon_Hologon/00_pag.htm
This lenses are harder to produce.

I learned at a optical design course held by some Zeiss lens designers that strong refraction angles are a property of an tensed optical surfaces, and should be avoided. This is not the same as strong lens curvature!


PostPosted: Wed Jul 23, 2014 8:45 am    Post subject: Reply with quote
Gerald wrote:
..
And I learned not to pay much attention to the opinions of owners of expensive and exotic lenses. In general, those people "think" with the heart and not the brain. People usually get enchanted when they buy a lens that costs more than $1000. Would you expect them to say they made a bad deal? In addition, I also know it is not easy to evaluate objectively whether a lens is exceptionally sharp or simply is average. Of course, who buys a $1300 lens will always say that it is very sharp...


There I completely agree Smile
People who paid a lot of money often think they have bought the best. And therefore they don't accept any negative influence.

I would love to own a Sony STF 135 - not for reproduction images, but for flowers, people and other smaller objects.
I like its special bokeh, and that lens don´t need to be a perfect lens for every type of photography.
But cause I don´t want to pay that much money, and cause I am a notoriuos tinkerer, I make my own apodization lenses.


PostPosted: Wed Jul 23, 2014 9:47 am    Post subject: Reply with quote
While I'm on the scientific side and thus measurements for me are important, if the measurement method is not reliable it does not serve much. Furthermore, if some properties are not measurable (like creaminess, sense of 3D, etc), then it's not worth to measure it except for marketing purposes. So, shooting 500 pictures (analog times: should be 5000 at least on digital Smile ) is a good way of understanding a lens.

Said that, in this case we are amateurs appreciating now properties that maybe were not so considered when you did not have any choice. It's like "traditional" food: one century ago poor people cannot choose what to eat, and their poor dinner is now considered extraordinary (even if greasy, poor in vitamins, etc). I'm sure that first Petzval users would have exchanged their lens for a 18-55 kit zoom, like my grandparents would have liked a McDonalds hamburger more than usual polenta and cheese Wink.

But: I do not know how many of you make a living from old lenses. I just have fun with them, and if I only had free time, I would build myself my own low-quality lenses only for the sake of experimenting (actually, I did some quick attempt).


PostPosted: Wed Jul 23, 2014 9:48 am    Post subject: Reply with quote
ZoneV wrote:
.....I make my own apodization lenses.

Out of topic, but...
If it's not a secret, are you using the same slide film method?
What film proved to be the best for making the apodization filter?


PostPosted: Wed Jul 23, 2014 11:12 am    Post subject: Reply with quote
dan_ wrote:
...What film proved to be the best for making the apodization filter?


Yes, slide film was my first satisfying lens apodization filter method. I think the Agfa Precisa 100 was quite good.
Problem was that either the slide film recording, the film itself or the film development caused colored "black" - it was not neutral.
Furthermore the color fades away. Silver based BW film would be better there - but I found no clear enough film. Probably document film (Kodak Technopan or Agfa Ortho..) would be better.
I work currently to creat better filters. I want at least one apodiszation lens in my setup, probably a fast tele lens, like the Porst 135mm/1.8.


PostPosted: Wed Jul 23, 2014 11:27 am    Post subject: Reply with quote
Microfilm such as Agfa Copex or Kodak Imagelink HQ is perfectly clear when developed.


PostPosted: Wed Jul 23, 2014 11:31 am    Post subject: Reply with quote
Thank you iangreenhalgh1, I think I have one or two rolls Agfa Copex somewhere in my tinker shelfs. Bought different films for those tests, but did not perform all the film tests.


PostPosted: Wed Jul 23, 2014 11:43 am    Post subject: Reply with quote
Thank you both.
I have some Ilford Ortho 4x5 (not the Ortho plus) technical film in the fridge and never tried it. Have you any experience with it? Would it be suitable? Couldn't find any info about it.


PostPosted: Wed Jul 23, 2014 11:46 am    Post subject: Reply with quote
I have shot some ilford ortho but in 2x3 I cut up some 9x12) but can't remember how it turned out, sorry. I think it was clear but with a blue tint.

I might have to try making an apodisation filter myself, I figure display a circular gradient image in photoshop, take a picture of it.

I have loads of 135mm lenses I could sacrifice one. Or perhaps the Minolta 3.5/100 I have that has a broken iris.


PostPosted: Wed Jul 23, 2014 12:28 pm    Post subject: Reply with quote
Thanks a lot, Ian.
I'll give it a try.


PostPosted: Wed Jul 23, 2014 1:14 pm    Post subject: Reply with quote
Tedat wrote:
after that you got a link to a website where they tested the same lens and provided their own MTF chart (in english!).. but since those charts don't proove your opinion.. you just ignore them.

I really believe in the validity of the measurement of MTF when done properly. Unfortunately, the lens manufacturers often cheat shamelessly, so it is necessary to see with great care the MTF curves published by them. In the case of Sony STF 135mm T4.5 lens there is a clear discrepancy between the curves published by Sony and samples of actual images, as those in Kurt Munger's site, for example. I found several photos on the Internet that confirm the observations of Munger that Sony STF 135mm T4.5 lens is soft in the corners. Below is one of these photos showing how the corner is much softer than the center.

Link of the original picture:
https://www.flickr.com/photos/tnanba/8254273799/sizes/o/

Full image:


Center & Upper left corner - 100% crop:


Bottom line: The MTF curves published by Sony and Photozone are worthless because they are in clear contradiction with the real pictures produced by the Sony 135mm T4.5 STF lens. In my opinion, those MTF curves are just pieces of commercial propaganda.

Tedat wrote:

My personal conclusion: testing lenses and reading charts is much more important for you than using a lens for photos. If tests or charts don't proof your point, they are wrong. It's pretty useless to discuss anything with you, so I will stop here and ignore all your future posts.. they are pretty useless for me, you prooved that clearly.


To say what? Sorry if I disappointed you. I am just trying to understand lenses better, and not trying to "proving" anything.


PostPosted: Wed Jul 23, 2014 2:26 pm    Post subject: Reply with quote
It is quite clear to me now that the Sony lens 135mm T4.5 STF is soft in the corners wide open. However, someone suggested that the lens was optimized not for infinity but for short distances, what would explain its poor performance for large distances.

As I discussed in a previous post, the concept of "infinity" in terms of correction of aberrations is any distance greater than 30 to 40 times the focal length, which is about 4 to 5m for a 135mm lens. So, if the performance of a 135mm lens is poor for infinity, it is poor for 4m, too. But to not remain any doubt, I searched, and managed to find some photos that allow good evaluation of the performance of the Sony 135mm T4.5 STF lens at really short distances. The link to the original photo:
https://www.flickr.com/photos/tnanba/10918366956/sizes/o/

Full image (downsized to 1024 x 683):


Apparently, the photographer wanted to photograph the dead leaf but missed the focus! Well that is not very important for our purposes, because the goal is to observe how the lens renders the fine detail of the grass. The first thing to determine is where is the intersection of the plane of focus with the soil surface.

Quote:

Plane of Focus

The Plane of Focus (PoF) is an imaginary two dimensional plane in front of the camera at the point of focus. The PoF Represents the theoretical plane of sharpest focus and lies in the depth of field. The PoF lies parallel to the sensor (and perpendicular to the optical axis). Except in some special cases (tilt & shift lenses and bellows cameras), the PoF remains in the same position relative to the plane When the camera tilts or changes its position / angle sensor.

Quoted from: http://www.photokonnexion.com/?page_id=15663

I traced a red line on the picture above just to show the intersection of the plane of focus with the soil surface. The image points along that line are precisely those better focused, and therefore the sharpest.



Using the red line as a reference, I took crops from the center and left and right edges. Comparing side-by- side the edges with the center, it is quite clear that the edges are significantly softer than the center. I.e., the Sony 135mm T4.5 STF has indeed a poor performance at the edges for both large and small distances.

Center & Left Edge:


Center & Right Edge:
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